Ah, yr elen. I remember that as an irritating sideways excursion near the end of the Welsh 3000s just as the end seems near. Stand back from the map and you will see the Carnedds make an arc, a superb high level walk, including your peaks - but the best place to start is in the east, makes a logical circuit. I would suggest as good as the Snowdon Horseshoe, without the Crib Goch drama, and without the crowds.
So, start from Rowen, limited parking at the east end, walk up to the bwlch y deufaen, then just keep going, climbing at a moderate incline over Foel Fras to Llywellyn, nipping off to the irritating yr Elen if you must, then over the top of Craig yr Ysfa, on to Penyr Lythrig, then dropping down to Llyn Eigiau, follow the stream on down to the main road at Talybont eventually. I completed the circuit on field paths back to my car, but there is an occasional bus if you get your timing right. Without any excursions to Dafydd, about 22 or 23 miles, around 4,500 feet of ascent, allow about eight hours to give you time to enjoy a whole day on the tops. Definitely better than trying to codge a route up from the west.